The direct development of La-5 fighter was Lavochkin La-5FN. By using the radial M-82FN engine the speed and altitude performance of the aircraft improved. It was some 65 Km/h faster then Bf-109G. The further development led to even faster La-7 fighter. The La-5FN was used in combat by the end of 1943.
The arnament changed to two 20 mm canons which become standard fr the late versions of Lavochkins aircraft.
More about Lavochkin LA-5FN on Wikipedia
June 2009